Muffler



April 5, 1938. R. J. MdcKENzlE MUFFLER 2 Sheets-Shee l Filed Deo. 28, 1936 April 5, 1938. R. J. MacKENZ|E 2,112,964

MUFFLER Filed DeO. 28, 1956 2 SheeS-Sheefl 2 Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE Application December 28, 1936, Serial No. 117,761

Claims.

This invention relates to improvements in mufllers or silencers for internal combustion engines.

In application No. 723,735 filed jointly in my name and in the name of L. L. Haas, a muffler is shown in which a restricted channel or bottle neck passage is formed by pressing portions of the ends of an intermediate shell into engagement with an inner shell extending through the intermediate shell. This leaves longitudinal portions of the intermediate shell between .such pressed in portions, which are spaced from the inner shell to form channels or bottle necks. kAccording to this prior construction, such channels or bottle neckscan be formed at one or both ends of the intermediate shell. It is some times necessary, however, in order to produce satisfactory silencing to provide a channel or bottleneck in a part of an Yintermediate shell spaced vfrom the ends thereof, for example, in case it becomes necessary to provide three or more series of bottle necks together with their cooperating resonance chambers.

One .of the objects of this invention is to provide a construction by means of which an intermediate shell may be provided with a channel or bottle neck at a portion thereof spaced Vfrom the ends kof the intermediate shell. It is also van object of this invention to provide an intermediate muffler shell having portions formed to produce with an inner shell channels capable of cooperating with three or more bottle neck type of resonance chambers. Another object of this invention is to provide a construction of this kind by means of which the channels or bottle necks can be produced without the use oi additional parts. Other objects of the invention will appear from the following description and claims.

In the accompanying drawings:

Fig. 1 is a longitudinal sectional View of a part of a muler embodying this invention.

Fig. 2 is a similar view of the remainder of the muffler, this figure being substantially a continuancc of Fig. 1.

Fig. 3 is a fragmentary longitudinal view `of a portion of an intermediate shell prior to the pressing of the same into the desired shape to produce a passage or bottle neck for a resonance chamber.

Figs. 4, 5, and 6 are tranverse sectional views of the muler taken respectively on lines 4-4, 5 5, and 6-6, Fig. l.

I have illustrated in the drawings one type of muler to which my invention may be applied,

but it will be understood that it is not intended to limit this invention to the particular type of muffler illustrated. The muler shown has a casing or housing comprising an outer shell 9 and heads I0 and II arranged at opposite ends thereof and secured to the outer shell 9. The head I0 is provided with a tubular inlet portion or duct I2 to which an exhaust pipe leading from the engine may be connected and the head II is provided with a tubular duct or connection I4 to which a tail pipe may be connected. The mufller also has an inner shell or duct I5 provided at intervals with groups of apertures or perforations I6 of any suitable or desired form, the several groups of perforations being preferably separated by imperforate portions of the muiiler. One end of the inner shell may be suitably secured to the head I0 to receive exhaust gases from the inlet duct I2, and the opposite end of the inner shell may be similarly arranged u to discharge gases into the discharge duct I4, both ends of the inner shell being telescopically arranged in the ducts in the particular construction illustrated. The muffler also includes one or more intermediate shells extending about the inner shell and spaced therefrom and from the outer shell to form chambers for sound waves and gases which pass out of the inner shell I5 through the perforations or apertures I 6. The

muler shown is provided with a tubular intermediate shell IB, one end of which is provided with inwardly bent longitudinally extending channeled portions I9 which may be secured to an imperforate part of the inner shell I5. Between these inwardly bent channels are arranged portions 20 of the intermediate shell which are spaced from the inner shell and thus form channels or bottle necks 2|, Fig. 4, which connect an inner chamber 22, arranged between the inner shell I5 and the intermediate shell I8, with a chamber 23 arranged between the intermediate shell I8 and the outer shell 9. 'Ihis latter chamber terminates at one end in a baille or transverse partition 24 extending from the intermediate shell to the outer shell. This portion of the construction is similar to ,that disclosed in the aforementioned application No. 723,735.

At the other end of this intermediate shell, another chamber 25 is formed between the intermediate shell and the inner shell I5 and gases entering into this chamber may be discharged through the open rear end of this chamber into a resonance chamber 21 extending from the head II to another baffle or transverse partition 28 arranged between the intermediate and outer shells.

The muffler is preferably also provided with high frequency resonance chambers, which in the particular construction shown, are formed between the inner shell I5 and another intermediate shell 30. This latter shell may be formed in any suitable or desired manner, for example, shells such as shown in copending application No. 89,606, led in the names of R'oy J. Mac- Kenzie, Lucien L. Haas, and Gail C. Starkweather, may be employed. In the construction shown, the shell is formed of two or more sections having longitudinally extending flanges 3| welded or otherwise secured together so that the several sections together form a complete intermediate shell. If a plurality of separated resonance chambers is desired, the sections of the shell 30 may be provided with integral inwardly extending parts or waist portions 32, extending into contact with the inner shell I5, thus forming two resonance chambers 33 and 34, by means of which certain high frequency sound waves may be eliminated by destructive interference. The outer walls of the intermediate shell also form a portion of the inner walls of the resonance chamber 21.

The various parts of the muiiler which have thus far been described have heretofore been used in the construction of muiiiers and do not of themselves constitute a part of this invention.

It will be noted that by means of the construction described, there is formed between the bales 24 and 28 an outer chamber 35 spaced between the outer chambers 23 and 21. It may be desirable in order to silence certain sounds present in the exhaust of an engine to utilize this third outer chamber 35 as a part of a bottle neck type of resonance chamber, independently of the outer chambers 23 and 21. For this purpose, I provide between the ends of the intermediate shell I8 a channel or bottle neck leading from one of the inner chambers to the outer chamber 35 and in order to provide such channel or bottle neck without using an additional intermediate shell, I provide the following construction.

The intermediate shell I8 is provided with one or more circumferentially extending slits 31, two being employed in the construction illustrated, which are arranged at opposite sides of the inner shell at the zone of said duct or inner shell I5 which is imperforate, and which slits are separated by unslitted portions of this shell. The unslitted portions of the shell are then pressed inwardly to a suicient extent to form longitudinally extending grooves 38 in the intermediate shell, the inner portions of the grooves preferably contacting with the inner shell I5. This leaves the portion of the metal of the intermediate shell which terminates at the slits 31 spaced from the inner shell as shown at 39 to form channels or bottle necks communicating with the inner chamber 22. An annular band or part of the metal of the intermediate shell at the righthand side of the slits 31, in the particular construction shown, is pressed inwardly into contact with the imperforate zone of the inner shell I5, as shown at 40, thus forming an end wall for the inner chamber 25. This leaves the channels or bottle necks 39 which terminate at the slits 31, along the imperforate zone of sheet I5, in open ends which communicate with the outer chamber 35, and the other ends of these channels communicate with the chamber 22, so that sound waves from the inner chamber 22 may pass through the channels or bottle necks 39 into the resonance chamber 35.

In order to adapt a muler to cooperate with an engine producing certain noises or sounds to be eliminated, it may some times be necessary to provide three outer resonance chambers which may have to be tuned so that each chamber opcrates to destroy a certain band of sound waves occurring in the exhaust. In order to tune these chambers to operate on different sound waves, the baflies 24 and 28 may be located at different distances from each other and from the heads I 0 and II, and the bottle necks or channels 20 may be varied in length and cross sectional area to cooperate with the outer chamber 23. Similarly the channels or bottle necks 39 formed in an intermediate portion of the shell I8 may be varied in length and cross sectional area by varying the lengths and widths of the inwardly pressed grooves 31, to enable the bottle necks 39 to cooperate to the best advantage with the outer chamber 35. The length of the annular channel between the right-hand end of the intermediate shell I8 and the imperforate portion of the inner shell surrounded by this part of the intermediate shell may also vary in length. This muiiier may, therefore, be used to good advantage where three different types of low frequency sound waves occur in an exhaust which must be destroyed by means of three outer resonance chambers. It will, of course, be obvious that the construction herein described is equally applicable to mufliers in which more than three outer resonance chambers are provided, as well as to muflers having less than three resonance chambers, since it may be desirable to form a channel or bottle neck in a part of an intermediate shell between the ends thereof.

The construction described can be readily produced, and it will be noted that the channel or bottle neck between the ends of the shell can be produced without using any additional parts, it being merely necessary to slit and form the intermediate shell in the manner described. It is, of course, not necessary to form the groove or grooves 38 in the intermediate shell, since if, after forming one or more slits 31 in the shell, the formation of the annular groove or depression 40 will establish communication between the chambers 22 and 35.

I claim as my invention:

1. A muiiler having outer, intermediate and inner shells, heads secured to the ends of the outer shell, the inner shell being provided with perforations, said shells forming between them i inner and outer chambers and the inner shell forming a passage for gases, said intermediate shell having a slit therein which extends generally peripherally through a part only of the periphery of said shell, the wall of said intermediate shell along one side of said slit extending inwardly toward the inner shell, to form an open- CLL) cumferentially through a part only of the circumference of said shell, the wall of said intermediate shell immediately adjacent to and along one side vof said slit extending inwardly toward the inner shell, to form an opening in said intermediate shell at said slit through which gases and sound waves may ilow from an intermediate to an outer chamber, said intermediate shell at the opposite side of the slit also being inwardly constricted at the ends of said slit for a short distance from the slit, the wall of said inner shell being imperforate for a substantial distance in both directions endwise thereof from said slit.

3. A muiiier having outer, intermediate and inner shells, heads secured to the ends of the outer shell, the inner shell being provided with perforations, said shells forming between them inner and outer chambers and the inner shell forming a passage for gases, said intermediate shell having a series of slits in approximate tandem arrangement and extending in a direction peripherally of said shell and spaced apart end for end, the wall of the intermediate shell immediately adjacent .to and bordering one side of said lseries of slits extending inwardly toward said inner shell, to form openings at the other side of said slits to establish communication between an inner and an outer chamber, the wall of said inner shell being imperforate in the zone at the slit and extending a substantial distance endwise of the inner shell in both directions from said slit.

4. A tubular muiiler shell having intermediate of `its ends a slit which extends generally peripherally of the shell but through a part only of the periphery of said shell, a part of the metal of said shell at one side of said shell being constricted out of the contour of the remain-der of said shell along the slit to form an opening at said slit, and other parts of the metal of said shell at the other side of said slit and at opposite ends of said slit also being constricted inwardly of the shell for a substantial distance endwise along the shell, to form in the interior of said shell a channel of substantial length terminating in the opening at said slit.

5. A tubular muilier shell having a slit .therein which extends circumferentially through a part only of the circumference of said shell, said shell along one side of said slit extending inwardly and providing with the portion of the shell along the opposite side of said slit an enlarged opening at said slit, said shell having a longitudinally extending groove at said opposite side of said slit between opposite ends of said slit and forming on the interior of said shell a channel terminating in said enlarged opening.

6. A muffler having outer, intermediate and inner shells with spaces between them, heads secured to the ends of the outer shell, the inner shell being provided with perforations, said intermediate shell having therein intermediate of its ends a slit which extends circumferentially .through a part only of the circumference of that shell, and also having its wall on one side of and bordering said slit spaced from said inner shell 4to form withsaid inner shell a passage from the slit to the chamber between the inner and intermediate shells at that side of the slit, the wall of said intermediate shell in the circumferential zone immediately at the opposite side of said slit from said passage being constricted towards rthe periphery of the inner shell in a direction circumerentially of the inner shell until it substantially closes communication between the portions of the space provided between the intermediate and inner shells at opposite sides of said slit, the portion of said intermediate shell at the ends of the slit but on the same side of said slit as said passage, being constrcted into approximate contact with said inner shell for a short distance from said slit measured in a direction endwise of the inner shell to define the side edge walls of said passage, the portion of said inner shell along said passage being substantially imperforate, and said passage at the slit end thereof opening into the space between said outer and intermediate shells.

'7. kA muiiier having outer, intermediate and inner shells, heads secured to the ends of the outer shell, the inner shell being provided with perforations, said shells being spaced apart, baffles between said outer and intermediate shells forming with said heads a plurality of outer chambers, said intermediate shell having therein intermediate of its ends a slit which extends circumferentially through a part only of the circumference of that shell, with the wall ofsaid intermediate shell on one side of and bordering said slit spaced from said inner shell to form with that shell a passage leading from said slit to the chamber between the inner and intermediate shells at that side of the slit, the wall of said intermediate shell in the circumferential zone immediately at the opposite side of the slit from said passage being constricted until it substantially closes communication between the chambers provided at opposite si-des of the slit between said inner and intermediate shells, the portion of said intermediate shell at the ends of the slit, but on the same side of said slit as said passage, being constricted into approximate contact with said inner shell for a short distance from said slit measured in a direction endwise of said inner shell, to dene the side edge walls of said passage, the end of said passage at said slit opening into the space between the intermediate and outer shells and between said baffles, the portion of the wall of the inner shell in the zone along said passage being imperforate.

8. A muiiler comprising a casing with closed ends, a conduit passing through said casing from end to end, a shell within said casing and interposed between the peripheral casing wall and said conduit and largely spaced from said conduit and casing wall, bafile means interposed between said casing wall and said shell so as to divide the space between the casing wall and shell into a plurality of chambers disposed in tandem arrangement along the casing, said shell having intermediate of its ends a slit extending generally in a peripheral direction for a part only of the periphery of said shell, the portion of said shell along and bordering one side of said slit extending inwardly towards said conduit, and the portion of said shell along the opposite side of said slit being spaced from sai-d conduit to provide a passage between the outer chamber at the slit and a compartment between said conduit and l said shell, said conduit being apertured in the portion along said compartment but imperforate in the peripheral zone adjacent said slit and for a substantial distance from said slit along said spaced portion of the shell, whereby communication will be established between said conduit and said compartment and from the latter through the opening provided by said slit into the chamber at said slit.

9. A muier comprising a casing having an inlet at one end and an outlet at the other end, a pipe within said casing and conducting gases through the casing from the inlet to the outlet and intermediate of its end spaced from the peripheral casing wall, a shell disposed around said pipe within said casing and spaced largely from the peripheral wall of said casing and from said pipe, baille means interposed between shell and the peripheral wall of said casing for dividing the space between the peripheral casing and said shell into a plurality of chambers arranged in succession along said casing, said shell at a point intermediate of its ends and within one of said chambers having a slit extending generally in a direction peripherally of the shell and for a portion only of its periphery, said shell along said slit at one side thereof extending into contact with said pipe, and at the other side of and bordering said slit spaced from said pipe, said shell having portions at the ends of said slit and along the sides of said space portion making contact with said pipe whereby the spaced portion of said shell along the slit will form with the pipe beneath it, an elongated bottle neck passage opening outwardly through the slit into an outer chamber between the shell and the casing wall, and at its other end opening into the space between said shell and pipe, said last named space being connected at a substantial distance from said slit to the interior of said pipe, whereby gases may pass from said pipe into said last-named space, and which said last-named space communicates through said passage with an outer chamber.

l). A muffler comprising a casing having an inlet at one end and an outlet at the other end, a pipe within said casing and conducting gases through the casing from the inlet to the outlet and intermediate of its ends spaced from the peripheral casing wall, a shell disposed around said pipe within said casing and spaced largely from the peripheral wall of said casing and from said pipe, baffle means interposed between said shell and the peripheral wall of said casing for dividing the space betwen the peripheral casing and said shell into a plurality of chambers arranged in succession along said casing, said shell at a point intermediate of its ends and within one of said chambers having a slit extending generally in a direction peripherally of the shell and for a portion only of its periphery, the portion of said shell bordering one side of said slit extending inwardly into contact with said pipe around the entire pew riphery of said pipe, and the portion of said shell along and bordering the opposite side of said slit being spaced from said pipe, whereby the space between said shell and pipe at the side of the slit having the spaced portion of the shell may communicate with an outer chamber through said slit, and said pipe having a passage communieating with said last-named space at a substantial distance away from said slit.

l1. A muffler comprising a casing having an inlet at one end and an outlet at the other end, a pipe within said casing and conducting gases through the casing from the inlet to the outlet and intermediate or" its ends spaced from the pe ripheral casing wall, a shell disposed around said pipe within said casing and spaced largely from the peripheral wall of said casing and from said pipe, baiile means interposed between said shell and the peripheral wall of said casing for dividing the space between the peripheral casing and said shell into a plurality of chambers arranged in succession along said casing, said shell at a point intermediate of its ends and within one of said chambers having a slit extending generally in a direction peripherally of the shell and for a portion only of its periphery, the portion of said shell bordering one side of said slit extending inwardly into contact with said pipe around the entire periphery of said pipe, and the portion of said shell along and bordering the opposite side of said slit being spaced from said pipe, the portion of said shell at the ends of said slit extending into contact with said pipe for a substantial distance along the sides of the spaced portion of said shell from said slit, so as to provide a passage from an outer chamber through said slit to a compartment between said pipe and said shell beyond said portion contacting the said pipe at the side of the slit which is spaced from the pipe, said pipe being apertured in the portion along said compartment and imperforate in the zone adjacent said slit, whereby the space between said shell and pipe at the side of the slit having the spaced portion of the shell may communicate with an outer chamber through said slit, and said pipe having a passage communicating with said last-named space at a substantial distance away from said slit.

12. A muflier having telescoping outer, intermediate and inner shells largely spaced from one another at intervals throughout their length, baiiie means interposed between the outer and intermediate shells intermediate of the ends of the intermediate shell, so as to divide the space between the outer and intermediate shells into a plurality of chambers arranged in succession along the outer shell, the intermediate shell at a point in one of said chambers having a slit extending in a direction generally peripherally of the intermediate shell but for a portion only of its periphery, the intermediate shell at one side of said slit being constricted into contact with said inner shell around its entire periphery, the portion of the intermediate shell at the opposite side of said slit being spaced from the inner shell along said slit and constricted into Contact with the inner shell at the ends of said slit, whereby the compartment formed between the inner and intermediate shells at that side of the slit which has the intermediate shell spaced from the inner shell along the slit, will communicate with an outer chamber through the passage formed along the inner shell from the slit by the l unconstricted portion of said intermediate shell adjacent the slit, said inner shell communicating with said compartment at a substantial distance from said slit, and said inner shell being connected to the outer shell for conducting gases through the outer shell from end to end thereof.

13. A muiiier comprising a casing having an inlet at one end and an outlet at the other end, a pipe within said casing for conducting gases therethrough from said inlet to said outlet, a shell within said casing and throughout its length spaced largely from said-pipe and from said the peripheral wall of said casing, said shell having, intermediate of its ends, a slit extending generally in a direction peripherally thereof but for a portion only of its periphery, a portion of said shell at one side of said slit and immediately adjacent the slit being constricted into contact with said pipe for substantially the entire periphery of said pipe so as to obstruct direct communication from end to end of said shell, the portion of said shell bordering the opposite side of said slit being spaced from said pipe along said slit and at the ends ofthe slit constricted into` contact with said pipe for a substantial distance measured in a direction endwise of the pipe, sufficiently to form a bottle neck passage from the slit endwise of the pipe for a substantial distance and opening into the compartment formed by the space between a continuation of said shell and said pipe, said pipe having com.- munication with said compartment solely beyond said bottle neck passage and from said compartment through said bottle neck passage to a chamber between said shell and the peripheral Wall of said casing.

14. A muffler comprising a casing having an inlet at one end and an outlet at the other end, a pipe within said casing for conducting gases through said casing from the inlet to the outlet, a shell within said casing surrounding said pipe and largely spaced from said pipe and from the peripheral wall of said casing, so as to provide an outer space between the peripheral wall of the casing and said shell and an inner space between the pipe and said shell, said shell at a point intermediate of its ends being provided with a plurality of slits extending generallyin a direction peripherally of the pipe and arranged in tandem to one another with unslitted portions between them, the portion of said shell at one side of and bordering said slits being`constricted into contact with said pipe, and at the opposite side of said slit being spaced from said pipe along said slits and constrlcted into contact with said pipe between the ends of said slits for a distance lengthwise of the pipe sufliciently to form bottle neck passages opening through said slits and establishing communication between an outer space at the slit and an inner space at the side of the slit having the bottle neck passage,

said pipe having communication with said last named inner space solely beyond said bottle neck passage.

15. A muiiler comprising a casing having an inlet at one end and an outlet at the other end thereof, a pipe within said casing for conducting exhaust gases between said inlet and outlet, a shell also within said casing and largely spaced from said pipe and the peripheral wall of said lcasing but terminating at both ends in spaced;

relation to the ends of said casing, baille means between said shell and the peripheral wall of said casing for dividing the space between said shell and said peripheral casing wall into a plurality of chambers arranged in succession along the casing, said shell at its ends opening into the end chambers of said plurality of chambers, the portion of said shell forming a wall of an intermediate one of said plurality of chambers having therein a slit progressing generally in a direction peripherally of the shell but for a portion only of its periphery, the portion of said shell along one side of said slit being constricted into contact with said pipe for at least approximately the full length of said slit, and along the other side of said slit being spaced from said pipe, said shell at the ends of said slit being also constricted into contact with said pipe at said other side of said slii'l for a distance suicient to form with said spaced portion of the shell along the slit a bottle neck passage opening through said slit into said intermediate one of said chambers, and said pipe being apertured into the space between it and said shell but solely at a substantial distance away from said slit.

ROY J. MACKENZIE. 

